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/* $OpenBSD: hash_func.c,v 1.11 2016/05/29 20:47:49 guenther Exp $ */ |
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/*- |
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* Copyright (c) 1990, 1993 |
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* The Regents of the University of California. All rights reserved. |
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* |
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* This code is derived from software contributed to Berkeley by |
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* Margo Seltzer. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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#include <sys/types.h> |
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#include <db.h> |
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/* Chris Torek's hash function. */ |
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u_int32_t |
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__default_hash(const void *key, size_t len) |
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{ |
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u_int32_t h, loop; |
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u_int8_t *k; |
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#define HASH4a h = (h << 5) - h + *k++; |
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#define HASH4b h = (h << 5) + h + *k++; |
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#define HASH4 HASH4b |
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h = 0; |
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k = (u_int8_t *)key; |
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✓✗ |
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if (len > 0) { |
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loop = (len + 8 - 1) >> 3; |
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✓✓✓✓
✓✓✓✓
✗ |
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switch (len & (8 - 1)) { |
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case 0: |
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do { /* All fall throughs */ |
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HASH4; |
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case 7: |
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HASH4; |
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case 6: |
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HASH4; |
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case 5: |
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HASH4; |
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case 4: |
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HASH4; |
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case 3: |
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HASH4; |
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case 2: |
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HASH4; |
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case 1: |
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HASH4; |
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✓✓ |
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} while (--loop); |
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} |
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} |
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return (h); |
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} |